Hubble bubble may explain different measurements of expansion rate of the universe: One way to determine the Hubble constant... is based on measuring the cosmic microwave background radiation... can also be derived from the movement of galaxies near the Milky Way, movement largely due to the expansion of the universe. "When you compare the results from the two methods, there is a deviation of about 9 percent..."
...The bubble describes regions of the universe where the density of matter falls below the cosmic average. "Until now knowledge of our cosmic neighbourhood has been too imprecise to determine whether or not we are in such a bubble", continues Dr. Marra. "But let's just assume for a moment that our Milky Way is located in a Hubble Bubble. Matter outside the bubble would then attract nearby galaxies so strongly that they would move more quickly than average. In this case we would measure a higher Hubble constant that would apply to our cosmic neighbourhood, but not to the universe as a whole."